One of the more common afflictions to affect aging eyes are cataracts, which cause gradually deteriorating vision. Advances in ophthalmic surgery allow many cataracts to be removed and vision restored.
Treating cataracts typically involves the removal of the clouded natural lens and replacement with an artificial lens. Removal of the lens requires an incision or tunnel to be made in and/or adjacent to the cornea and a phaco-emulsifier to be inserted into the eye. The phaco-emulsifier vibrates ultrasonically to liquify the lens. The emulsified lens is removed from the eye via aspiration and the artificial lens is then inserted. Modern phacoemulsifiers and aspirators have small cylindrical tips with coaxial passages, one for irrigation and the other for aspiration.
It is desirable that the incision or tunnel be as small as possible. Nevertheless, one potential problem with the emulsification and aspiration procedure is damage to the cornea when the tip of a phacoemulsifier or aspirator is inserted through the incision and/or is manipulated within the lens capsule. The tip can tear the incision slightly and complicate the healing process. In addition, a conventional tip does not always create a good seal with the incision, thereby leading to increased fluid loss.
One approach toward a solution to these problems is to provide a resilient sleeve around a rigid inner cannula. However, pressure at the corneal incision can crimp the sleeve and hinder effective irrigation and aspiration.